One of the key challenges for improving the capacity of wireless communications systems with large numbers of transmitter and/or receiver antennae is the large amount of channel state information that must be acquired. For example, with a 256-element base station antenna array and a 64-element mobile station antenna array, the channel matrix between the two devices has a dimension of 256×64, which would be practically impossible to estimate if channel estimation were performed on a per element basis.
There is, therefore, a need in the art to develop improved techniques for acquiring channel state information in massive MIMO systems with large numbers of transmitter and receiver antennas.